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Biomedical subjects

J R Mitchell

Publications and source records attributed to J R Mitchell.

At least 163 records · Page 9Linked to original sources
PubMed1981

Blood pressure reduction in elderly: a randomised controlled trial of methyldopa.

A total of 123 out of 549 elderly residents of local authority welfare homes in Nottinghamshire were found at screening to have a standing or lying diastolic blood pressure of 100 mm Hg or more. These 123 subjects were randomly allocated to simple observation or to treatment with methyldopa. The cumulative mortality was similar in the observed and treated groups and in the normotensive group from which the subjects had been separated. Thus moderate hypertension, whether treated or not, was not a major risk predictor in the elderly population studied.

Aged↗
PubMed1981

In vivo regulation of hepatic glutathione synthesis: effects of food deprivation or glutathione depletion by electrophilic compounds.

The increased glutathione turnover that occurs during fasting results from two mechanisms. Because of a decrease in the intrahepatic free glutathione: mixed disulfide ratio, which is apparently mediated by c-AMP, the free glutathione pool contracts and turns over more rapidly in order to maintain glutathione synthesis. In addition, glutathione consumption via the gamma-glutamyl cycle apparently is increased during fasting. Additional data indicate that an inability to stimulate further the rate of glutathione synthesis during fasting, rather than a reduction in glutathione synthesis are previously postulated, probably explains the increased susceptibility of fasted animals to tissue attack by electrophilic drug metabolites.

Acetaminophen↗
PubMed1981

Serum lipids in a teenage population: geographic, seasonal and familial factors.

The lipid results of a cross-sectional study of cardiovascular disease risk factors in over 600 13-18 year olds drawn from general practices in contrasting areas are reported. Differences were noted between the 3 practices, including a significant variation in the blood group distribution. HDL cholesterol showed a marked variation between the 3 practices which was unlikely to be due solely to seasonal variation. Alcohol consumption though not an univariate correlate of HDL cholesterol was however a strong partial correlate, as were age, height, sexual maturation, adiposity and smoking. Using 6 factors in each sex, 13% of the interchild variance of HDL cholesterol in boys could be explained in a multiple linear regression analysis, and 8% in girls. Including the practice variation as a further independent variable increased the explanation in 18% in boys and 15% in girls. An intraclass correlation (sib-sib) of 0.36 was found for HDL cholesterol, suggesting a strong familial influence. The implications of these results are discussed, along with the difficulties of screening for hyperlipidaemia in this age group.

Adolescent↗
PubMed1981

The diagnosis and management of patients admitted to hospital with acute breathlessness.

The authors have studied 352 emergency medical admissions during a summer period and 355 during the winter months to identify 177 patients who had been treated for breathlessness. Multiple and rapidly changing treatments have been taken to indicate diagnostic uncertainty. Using this model, the authors have shown that there is much more uncertainty in winter than in summer and that the working diagnosis of chest infection or asthma is particularly likely to be associated with multiple treatment. It is questionable whether the stereotyped descriptions of diseases in standard text books provide an adequate basis for emergency treatment decisions and it is considered that the diagnostic value of investigations such as chest radiography needs further careful scrutiny.

Acute Disease↗
PubMed1981

Regulation of hepatic glutathione turnover in rats in vivo and evidence for kinetic homogeneity of the hepatic glutathione pool.

The intracellular distribution of glutathione into kinetically distinct pools and the determinants of glutathione turnover were examined in vivo. Glutathione turnover was measured in individual, restrained rats with a biliary fistula by administration of acetaminophen to trap the previously labeled hepatic glutathione as an excretable acetaminophen adduct. Fasting for 48 h resulted in a decrease of hepatic glutathione from 4.7+/-0.9 to 3.6+/-0.8 mumol/g liver and a marked increase in the fractional rate of glutathione turnover from 0.19+/-0.04 to 0.43+/-0.07/h. Within 6 h following refeeding, the rate of glutathione turnover and the hepatic glutathione concentration returned to normal. The simultaneously determined specific activities of free intrahepatic glutathione and the acetaminophen-glutathione adduct in bile were identical, indicating that the hepatic glutathione pool is kinetically homogeneous. The synthesis of glutathione could, therefore, be estimated from the rate constant and the intrahepatic glutathione concentration. During fasting hepatic synthesis of glutathione increased from 0.86+/-0.17 to 1.50+/-0.23 mumol/g per h. In fed animals the administration of dibutyryl cyclic adenosine monophosphate and theophylline stimulated the rate of hepatic glutathione turnover similar to fasting. In contrast, glucose given intraduodenally to fasted animals decreased the rate of glutathione turnover. These data are consistent with the view that the increased glutathione turnover that occurs during fasting results from two mechanisms. Because of a decrease in the intrahepatic free glutathione/mixed disulfide ratio, which is apparently mediated by cyclic adenosine monophosphate, the free glutathione pool contracts and turns over more rapidly in order to maintain glutathione synthesis. In addition, glutathione consumption via the gamma-glutamyl cycle apparently is increased, which may be related to the increased uptake of amino acids for gluconeogenesis during fasting.

Acetaminophen↗
PubMed1981

Adolescents' use of mental health services in a comprehensive treatment facility: age, sex and mode of entry.

Data are presented from the clinical records of 185 adolescents who were admitted to the mental health service of a youth health center serving a community of military dependents. Eight and one-half per cent of the population made a first visit to the center during an eight month period. Midadolescence (ages 15-16) was the age period when patients began to refer themselves to mental health services in significant numbers. The importance of parents as referral sources decreased with age, while medical and school sources were important in all ages. The psychological morbidity in the target population was greater in midadolescence than in early and late adolescence and higher in females than in males. Females presented with more somatic and family problems, males more often with aggressive behavior problems.

Adolescent↗
PubMed1980

Randomised placebo-controlled trial comparing oxprenolol with disopyramide phosphate in immediate treatment of suspected myocardial infarction.

473 patients with suspected acute myocardial infarction were entered into a randomised, double-blind, placebo-controlled comparison of disopyramide phosphate, 150 mg three times a day, and oxprenolol, 40 mg three times a day. When analysed on an intension-to-treat basis there was no significant difference in 6-week mortality between the groups, but patients who were able to continue on the active medications fared better than the patients who had to be withdrawn. The withdrawal rate because of heart failure in patients randomised to receive disopyramide was significantly increased. Patients receiving this agent also showed a reduced number of arrhythmic episodes on 24-h tape recordings but this trend did not achieve statistical significance. The results show that the early use of either oxprenolol or disopyramide phosphate in patients with suspected acute myocardial infarction is unlikely to improve mortality.

Acute Disease↗
PubMed1980

Sulphinpyrazone in acute myocardial infarction: studies on cardiac rhythm and renal function.

Ninety-eight patients with acute myocardial infarction were randomly allocated to receive sulphinpyrazone 200 mg four times daily or placebo on admission to a coronary care unit. Twenty-four-hour electrocardiogram tape recordings showed no significant reduction in serious arrhythmias in the sulphinpyrazone-treated group. In addition to the expected all in serum urate concentration, patients taking sulphinpyrazone showed a persistent increase in their serum urea and creatinine concentrations when compared with those in the placebo groups (p < 0.05 and p < 0.01 respectively). These differences could not be accounted for by differences in the extent and severity of the infarction between the two groups. These results suggest that sulphinpyrazone has no discernible antiarrhythmic effect in acute myocardial infarction.

Arrhythmias, Cardiac↗